The present invention relates to a fiber optic connection and use thereof during measurement of intravascular pressure, and more specifically during measurement of pressure in a vessel of an atherosclerotic patient.
In connection with percutaneous transluminal angioplasti (PTA) and percutaneous transluminar coronar angioplasti (PTCA) of atherosclerotic patients it is often desirable to measure the pressure gradient in front of and behind the stenosis in the vessel. In the PTA-method a balloon catheter is used being inflated to dilate the vessel in the area in which the stenosis is situated. Besides enabling the determination of the existence of stenosis, the pressure measurement can also be used to determine the extension of the stenosis and to evaluate if the PTA-method has been successful.
A pressure sensor being mounted to a guide and connected to an electronic unit is described in the patent applications Nos. SE 85 001048, SE 86 02836-2 and SE 86 03304-0, to which are referred. The known pressure sensor comprises a guide-sensor portion, being intended for insertion into the body, and a connective portion, connecting the air channel disposed along the sensor-guide portion and the optic fiber to the electronic unit. The properties of the guide portion, i.e. its ability to search its way in the vessels, is determined by its flexibility, torsion resistance, radiopacity etc, while the connective portion is formed for easy handling outside the body. When measuring pressure the pressure sensor can easily be inserted to desired position in a catheter already inserted in a blood vessel. The size, i.e. the diameter, of the sensor guide portion is limited by the inner diameter of the catheter while the connective portion leading to the electronic unit can have the coarseness required for stability and easily handling since it is independent of dimension.
A drawback with the known pressure sensor, being mounted on a guide and connected to an electronic unit, is that it is not possible to change catheter, e.g. from a balloon catheter to a diagnostic catheter with the pressure sensor in its place in the vessel since the sensor guide portion is rigidly coupled to the connective portion of the electronic unit which means that the whole construction must be withdrawn if a catheter exchange is needed. The reason why it is desireable to have the pressure sensor placed in the vessel is that the stenosis should be passed as few times as possible for the safety of the patient. Another drawback is that it is not possible to first put the guide-sensor in place in the vessel and thereafter thread a catheter over it. With the known construction one has to first bring out the sensor-guide portion during catheter exchange, thereafter insert a conventional guide into the catheter, pull out the catheter with a conventional guide left in the vessel, thereafter proceed in the same way as for the insertion of the first catheter, i.e. thread over the new catheter, pull out the conventional guide and eventually insert the sensor-guide portion.
A possible solution on the problem would be a releaseable connection between the sensor-guide portion and the connective portion. Such a connection would have to establish pneumatic and optic connection between the two portions.